1. Field of the Invention
The subject invention provides an electric drive wheel assembly for a vehicle.
2. Description of the Prior Art
The electric drive wheel assemblies of the type described herein are typically utilized in military vehicles, as well as heavy construction equipment, such as lift trucks and cranes. Often, these vehicles must operate in off-road conditions, which require each wheel to be driven independently. Accordingly, each of the electric drive wheel assemblies of the vehicle incorporates an electric motor into the wheel assembly for providing a rotational movement thereto. The electric motor operates at a pre-determined rotational speed and torque. Therefore, a planetary gear system, often referred to as a reduction gear system, is coupled to the electric motor. The planetary gear system transmits the rotational movement from the electric motor to a wheel rim, while reducing rotational speed of the wheel rim relative to the electric motor and increasing the torque provided by the electric motor.
U.S. Pat. No. 3,812,928 issued to Rockwell et al., discloses an electric wheel assembly for a vehicle. The wheel assembly includes a non-rotating spindle attached to the vehicle along a rotational axis. An electric motor is concentric with the spindle and includes a stator surrounding and secured to the spindle. A rotor is concentric with the stator and is disposed about an outer periphery of the stator. The rotor is rotatable about the rotational axis relative to the stator. The stator and the rotor extend a predetermined axial distance along the rotational axis of the spindle. A wheel drive is rotatably supported by the spindle for rotation about the rotational axis. A first rotor support and a second rotor support are rotatably supported on the spindle. The first and second rotor supports are each supported by a rotor support bearing for rotation about the rotational axis of the spindle. The first rotor support is near the first end of the spindle and includes a flange extending radially outward along a first side of the electric motor to the rotor. The second rotor support is disposed opposite the electric motor, and also includes a flange extending radially outward along a second side of the electric motor to the rotor. A planetary gear system mechanically interconnects the second rotor support and the wheel drive for transmitting rotational movement of the rotor to the wheel drive.
Another example of an electric wheel assembly is provided in U.S. Pat. No. 6,328,123 issued to Niemann et al. This wheel assembly includes a spindle attached to an axle along a rotational axis. An electric motor is concentric with the spindle and includes a stator surrounding and secured to the spindle. The stator and the rotor are radially spaced from the spindle. A rotor is concentric with the stator and is disposed about an inner periphery of the stator and rotatable about the rotational axis relative to the stator. A wheel drive is rotatably supported by the spindle for rotation about the rotational axis. A rotor support is rotatably supported on the spindle near the second end thereof. The rotor support rotatably supports the rotor for rotation about the rotational axis. The rotor support includes a flange extending outwardly to the rotor along an outer edge of the electric motor near the second end of the spindle. The stator and the rotor extend inward toward the axle a predetermined axial distance along the rotational axis of the spindle. A planetary gear system mechanically interconnects the rotor support and the wheel drive for transmitting rotational movement of the rotor to the wheel drive.
The above prior art designs suffer from being overly large, cumbersome, and/or difficult to service. Accordingly, there remains a need to develop an electric wheel assembly that is relatively compact and can be easily serviced or modified.